fix camera screen black for samsung galaxy

The problem first :

Galaxy SII getting Unknown error by ErrorCallback Flash does not appear to work.

The problem second :

Samsung galaxy s2 goes black. Unable to take photos

 Now the solution to all these problems

Step 1 : Go to Settings

Step 2 : Select Applications ->Manage Applications or Apps

Step 3 : Select All (Look for ALL on top menu or swipe to the right to get to ALL)

Step 4 : Select Camera. Select Force Stop and Clear Data.

Step 5 : Go back to All and select Google Services Framework.
Select Clear Data.

Step 6 : Turn off (shut down) your phone and turn it back on.
Test your camera issue.